Art and apparatus for separating liquid gases



Dec. 9,1924.

W. B. DODDS rART AND APPARATUS FOR SEPARATING LIQUID GASES Filed May 25,1922 r patented Use.. 9% 1924o in-iran sra'ras rareur curi-uca;

l 'WVLLEM B. 'DODDS, OF JERSEY CITY, NEW JERSEY, ASSGNOR T0 SAFETY CAEHEATING 81: LIGHTING CUMPANY, A CORPORATIN 0F NEW JERSEY.,

AAlt'tl A 'ND APPRATUS FOR SEPARATING LIQUID GASES.,

Application led May 25, 1922. Serial No. 563,488,

To all 'whom t may concern."

Be it knownthat l, WILLIAM B. Donns, a citizen of the United States, anda resident of Jersey City, county of Hudson and State of New Jersey,have invented an lmprovement in the Art and Apparatus for SeparatingLiquid Gases.a of which the following is a` specification.

rllhis invention relates to the separation. of a gaseousfluid into itsconstituents and, more particularly, to apparatus and method forseparating liquefied gases by evaporation and rectification into theirrespective constituents.

provide a simple and compact apparatus for effecting the separation of aliquefied gas into its respective constituents and to provide efficientapparatus of flexible control and operation for obtaining ases of a highdegree of purity. Another o ject is to provide a practical method forobtaining gases of a high degree of purity and for insuring a positivecontrol of the degree of purity of product desired. Other objects willbe in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction andoperation, combinations of elements, arrangements of parts" and sequenceand relation of steps which are exemplified in the'structure hereinafterdescribed and the scope of the application of which willy be indicatedin the following claims.

In the accompanying drawing in which is shown one of various possibleembodiments of this invention,

" being preferably obtained from the heat of liquefaction of the fluidbeingliqueied. lin thc ensuing description thefeatures of this inventionwill be described in connection particularly with the liquefaction ofair and @ne of the objects of this invention is toY the subsequentevaporation thereof and rectification into oxygen and nitrogencReferring now to the drawings there is shown a rectifying column takingthe form preferably of a vertical container or c linder 10 provided` atits lower end witi an intake pipe 11 controlled by a valve 12 by meansof which the flow of air preferably in gaseous form through therectifying columnI may be'controlled. u v The apparatus is supplied withair under c pressure from, a manifold 18 in turn connected with asuitable source of supply. The air supplied to the manifold 13preferably undergoes certain preliminary stages which may comprise firstthe compression of air from atmospheric pressure and at -roomtemperature. During this compression the temperature of the air ismaterially raised and the compressed air may be preliminarily cooled toa temperature somewhat below normal while maintaining the increasedpressure resulting from the compressionn Suitable means Inay be employedtov purif or cleanse the air thus operated upon. hese preliminary stepsare not illustratively set forth .in the drawing and it is obvious thatthey may be Varied or replaced .by other operations. The air underpressure thus supplied the manifold 13 passes preferabl through aheat-transferring device whicli may conveniently comprise a plurality ofconcentrically arranged cylindrical shells'14, 16 and 17 in spacedrelation to form the'rebetween annular chambers 14-16 and 16-17 throughwhich fluid may be passed. Within the chamber 14--16 formed by the twoshells 14 and 16 is positioned a plurality of spirally woundcoilsextendin throughout the length of the column and connected at theirupper ends .to the manifold 13 thereby to permit the (passage throughthe coils 15 in a downwar direction of air under pressure supplied fromthe manifold. r1`he `lower' ends of the plurality of coils 15 dischargeinto the pipe 18 to which the pipe 11 with the controlling valve 12interposed therein is connected, thus to supply the rectitfying column10 with air under pressure and cooled bV th@ DSSg through theheat-transferring devlce.

- As conductive to a clear understanding of the functioning of theheat-transferring device above mentioned, it might at this point benoted that at the top of the rectifying column l there is provided adelivery or outlet pipe 19- through which the nitrogen or low boilingconstituent is withdrawn and that the column is provided at its basewith an outlet or delivery'pipe '2O through which the oxygen or highboiling constituent is adapted to be withdrawn. The pipe 19 is extendedas at 19a`to the bottom of the heat interchanger chamber 14-16 so thatthe low boiling constituent withdrawn therethrough may be passed incounter current with respect to the `air under pressure in the tubes 15through the chamber 14-l6, an outlet 21 at the upper end of the heatyinterchanger chamber being provided for eventually withdrawin the lowboiling constituent. The outlet pipe connected to the base of the column10 is extended as at 2()a to the bottom of the heat interchanger chamber16-17 through which the oxygen may be passed in an upward direction orin counter current relation with respect to the air in the tubes 15through the heat interchan er, an outlet 22 being provided at the top othe heat interchanger chamber for subsequently withdrawing the oxygen orhigh boiling constituent. The products of rectification emanating fromthe rectifying column 10 are thus made to further reduce the temperatureof the air supplied from the manifold 13 and, in effect, reduce itstemperature materially below normal. p

From the pipe 18, thus supplied with low temperature air under pressure,air is permitted to discharge through the Valve 12 controlled by thehandle 12, the valve 12 permittin the air to expand into the chamber 23pos1tioned at the interior lower portion of the rectifying column 10.During its expansion the air is cooled to the point of liquefaction andis preferably only partly liquefied and to an extent suflicie'nt so thatthe heat of liquefaction given up by the air in the subsequent stagesmay be transferred to the air undergoing evaporation and rectificationand to provide the latter with the heat of evaporation.

From the chamber. 23 the air passes through a distributing chamber 24 towhich the lower ends of a plurality of heat interchangin coils 25 areconnected, thus subdividing t 1e partially liquefied air into aplurality of relatively small streams. The coils 25 extend in an upwarddirection throughout substantially lthe entire extent of the containeror column 10 and at their upper ends are connected to a collectingchamber 26.` During the passage of the air upwardly through theplurality .of coils 25 its liquefaction is substantially completed aswill be more clear- 'ly hereinafter set forth, and from the collectingchamber 26 into which the individual coils 25 discharge a pipe 27conducts the liquefied air to an expansion valve diagrammaticallyindicated at 28 and-controlled as by the handle 28. From the expansionvalve 28 a pipe 29 leads the expanded fluid downwardly to thedistributing pipes 30 from which the fluid .is discharged 1n a pluralityof divergent streams and from which it is free to travel in a generaldownward direction through the rectifying column 10.

The spaces between lthe plurality of coils 25 and thecylinder l0 arefilled with a lurality of relatively small particles 31, tfieseparticles being of a material such as cop r, for example, having a highthermal condii tivity. The liquefied air expanded throu h the valve 28passes downwardly throu l1 tilie column 10 and through the partie es 31packed around the coils 25 and is subjected to a progressive evaporationand rectification. The plurality of particles 3l of high heatconductivity act to subdivide the downwardly moving fluid into .a largenumber of relatively small streams and thus act to insure intimatethermal contact between the upwardly moving fluid in the coils 25 andthe downwardly moving fluid in the rectifying column l0. The high heatconductivity of the particles 31, furthermore, insures an efficienttransfer of heat from the upwardly moving fluid in the coils 25 to thedownwardly moving fluid in the column 10. The resulting interchange ofheat, that is, the resulting'withdrawal of heat from the fluid in thecoils 25, causes the completion of the liquefaction of the fluid in thecoils 25 to take place and the heat thus absorbed by the downwardlymoving fluid is effective to boil off the low boiling constituent or thenitrogen. The resultant temperatures assumed in the rectifying column 10will be such that there exists' a progressively lower temperature as thefluid in the coils 25 moves toward the top, thus to complete theliquefaction thereof progressively, and .such that the downwardly movingfluid in the column l() meets with a progressively increasingtcmperature as it ap roaches the bottom of the column 10. The ownwardlymoving fluid is thus subjected to progressive evaporation andrectification, that is, the low boilin constituent is firstprogressively boiled o the vapors resulting therefrom rising through thecolumn 10 and being withdrawn through the pipe 19 at the top of thecolumn and assed through the heat interchanger chamer 14-16 ashereinbefore described. As the fluid passes downwardly through therectifying column 10 the low boiling constituent or the nitrogen isboiled ofi'A to a progressively greater degree and the downwardly movingfluid thus becomes progressively richer in its content of high boilinconstituent or oxygen. The latter is co lected in the bottom of thecolumn 10 lfrom which it may be withdrawn through the pipe 20 in gaseousor partly liquid form and passed upwardly throughl the heat interllll)lli changer chamber 16-17 to cool the incoming air as hereinbeforedescribed.

The effective operation as hereinbefore described is materiallydependent upon the maintenance at the base of the rectifying columnlO'of a temperature limit for the temperature lgradientv throughout thecolumn 10 sufficiently high to insure the progressive evaporation fromthe down-wardly moving fluid of the low boiling constituent; and amaterial lowering of this temperature limit existing at the base of thecolumn 10 results in the retention in the collected Huid at the base ofthe column of-an undesirable quantity of low boiling constituent ornitrogen. The degree of purity of the high boiling constituent or theoxygen withdrawn from 'the base of the column is thus materially anddetrimentally affected.

v In order, therefore, to insure a convenient control over thistemperature limit there is positioned within the column 10 and extendingthroughout a substantial range of the lower portions ofv the column 10what may be termed an auxiliary heat-transferring device taking `theform of the coil 32. The coil 32 has its lower end connected by means ofthe pipe 33, the valve 34 and the by-pass pipe 35 to the air-supplyingmanifold 13. The connection of the heating coil 32 therefore will beseen to be such that the air supplied thereto wil-l be by-passed aroundthe heattransferring devices 14-16 and 16-17 throughfwhich therectifying column is normally supplied with cooled air as hereinbeforedescribed. The air supplied to the coil 32 and foy-passed around theheat-transfer- V ring devices is expanded at the valve 34 and just priorto its entry into the coil 32, thus resulting in a material lowering ofthe `temperature as a result of the expansion. The drop in pressurebroughtabout by the valve 34 is preferably substantially the same as thedrop in pressure resulting the valve 12 supplying the coils 25 of therectifying column, but since the air expanded through the valve 34 isnot previously cooled to a subnormal temperature the resultanttemperature after expansion through the valve 34 will be relativelygreaterthan the temperature of the expanded air entering the coils 25 inthe rectifying column.

The' flow of this warmer air through the coil 32 may be so regulatedthat for given conditions of operation in the rectifying l column 10tending to cause a too great lowerrnitrogen will ing of the temperatureat the base 'of the column the air in the coil 32 may counteract thislowering in the temperature at the base of the column and may readjustandmaintain this temperature at the desired value at which the lowboilingr constituent` or be substantially entirely evaporated o'r boiledoff from the fluid collected in the base of the column. Thus the onetemperature limit in the column 10 necessary for efficient action and'for the attainment of a high degree of purity of hi h boilingconstituent or of oxygen may be su stantially automatically maintainedby adjusting the flow of the preliminarily uncooled air through the coil32.

As the expanded and relatively warmer air passes through the coil 32 toprevent the over-lowering of the temperature at the base of the columnthe air becomes materially cooled due to the transfer of heat therefromto the lower portions of the column and may be substantially liquefieddue to such cooling thereof. The coil 32 extends preferably throughout asufficient extentof the lower portion of the column 10 to bring aboutasubstantially uniform distribution 'throughout the lower portion in thecolumn 10 of its temperature readjusting effec-t. end of the coil 32 isconnected as by means of the pipes 36 Vto a convenient part of theapparatus where it may be subjected to ultimate evaporation andrectification together with the main flow of air through the apparatus.Thus, as shown in the drawings by way of illustration, the pipe 36 isconnected to the collectingchamber 26 into which the heat-transferringcoils 25 discharge vfrom whence the air as hereinbefore described ispassed through theexpansion valve 28 and discharged into the rectifyingcolumn. Thus it will be seen that the temperature at the base of thecolumn 10 is placed under positive control so that a high degree ofpurity of high boiling constituent or oxygen may be obtained and thatsuch control by means of a secondary stream of air is efficientlycarried out since the air after performing its controlling function isdischarged into-the column for rectification so that no heat lossesoccur. The operation may thus be carried on at exceedingly high thermalefficiency.

It may at this point be noted that the air throu h the coil 32 may beallowed to pass theret rough continuously at the proper rate of flow or,if desired, may be passed therethrough intermittently and only at suchtimes as the temperature at the base of the' column 10 has reached sucha value as to affect-the degree of purity of oxygen obtained at the baseof the column.

It will thus be seen that there has been provided in this invention amethod and apparatus for the separation of a gaseous fluid into itsconstituents in whichthe sev- The uppereral objects hereinbefore setforth are achieved and' in which many advantages are attained. It mayfurthermore be noted that there has been provided a method and apparatusin which a positive control in the. operating conditions may be readilyeffected to insure the attainment and maintenance of conditions ofoperation best adapted for the attainment of a high degree of purity ofproduct as well as of a high degree of eficiency.

As many possible embodiments might be made of the above invention and asmany changes might be made -in embodiment above set forth, it is to beunderstood that all matter hereinbefore set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.'

I claim:

1. The method of separating fluids which consists in cooling a gaseousfluid, passing the cooled fluid through successively colder` portionsof-a heat-transferring device to liquefy it, evaporating and rectifyingthe liquefied fluid through successively warmer portions of said deviceby causing the evaporating fluid to absorb its latent heat ofevaporation from the latent heat of liquefaction of the incoming fluid,whereby the constituent of said fluid having a low boiling point isevaporated first and withdrawn leaving fluid rich in the high boilingconstituent to be withdrawn separately from said rst constituent,heating said fluid rich in high boiling constituent prior to withdrawalby means of gaseous fluid of higher temperature than saidfirst-mentioned gaseous fluid whereby. said low boiling constituent insaid fluid rich in high boiling constituent is evaporated and separatedtherefrom and whereby said uncooled fluid is reduced in temperature, andin evaporating and rectifying said cooled fluid through successivelywarmerportions of said heattransferring device.

2. The method of separating fluids which consists in coolinga gaseousfluid, passing the cooled fluid through successively .colder portions ofa heat-transferring device to liquefy it, evaporating and rectifyingtheliquefied fluid through successively warmer portions of said device by'causing the evaporating fluid to absorb i'ts latent heat of evaporationfrom the latent heat ofv liquef'action of the incoming fluid whereby theconstituent of said` fluid having a low boiling point is evaporatedfirst leaving a fluid rich in the high boiling constituent, withdrawingthe evaporated low boiling constituent at a relatively cold point insaid device, collectin for subsequent withdrawal at a relative y' warmpoint in said .device said fluid rich in high boilin constituent,maintaining said collected. uid at a temperature substantially above theboiling point of said low boiling constituent by separatel passingtherethrough uncooled Huid where y said low boiling constituent in saidcollected fluid is substantially entirel boiled ofl' to leave theconstituentl ofy higi boiling point, and in withdrawing said constituentof high boiling point.

3. The method of separating fluidsy which consists in cooling a gaseousfluid, passing the cooled fluid through successively colder` portions ofa heat-transferring device to liquefy it, evaporating and rectifying theliquefied fluidl through successively warmer portions of said device bycausing the evaporating fluid to absorb its latent heat of evaporationfrom the latent heat of liquefaction of the incoming fluid whereby theconstituent of said fluid having a low boiling point is evaporated firstleaving a fluid rich in the high boiling constituent, withdrawing theevaporated low boiling constituent at a relatively cold point in saiddevice, collecting for subsequent withdrawal at a relatively warm pointin said device said fluid rich in high boiling constituent, preventingsaid heat-transferring device from attaining at such collecting point atemperature materially lower than that of the boiling point of-said lowboiling constituent by passing separately through said collecting pointof said device uncooled fluid whereby said low boiling constituent insaid collecting fluid is substantially entirely boiled ofi' and wherebySaid uncooled fluid is reduced in temperature, and subjecting the 'fluidthus reduced in temperature to evaporation and rectification in saidheattransferring device.

4. The method of separating fluids which consists in cooling a gaseousfluid through a first heat-transferring device, passing the cooled fluidthrough successively colder portions of a second heat-transferringdevice to liquefy it, passing the liquefied fluid through successivelywarmer portions of Said second device to evaporate and rectify theliquefied fluid whereby the constituent of said fluid having a lowboiling point is evaporated first and withdrawn leaving a fluid rich inthe high boiling constituent, collecting said fluid rich `in highboiling constituent in a relatively warm portion of said second device,passing gaseous fluid around said first heat-transferring device andseparately through said collected fluid rich in high boilingc'onstituentwhereby the low boiling constituent in said collected fluid issubstantially entirely boiled off and whereby said by-passed fluid isreduced in temperature, and evaporating and rectifying said by-passedfluid through successively warmer portions of said secondheat-transferring device.

5. VThe method of separating fluids which consists in cooling a gaseousfluid by passing it through a first heat-transferring device, passingthe cooled fluid through successively colder portions of a secondheat-transferring device to liquefy it. evaporating and rectifying theliquefied fluid through successively warmer portions of said seconddevice whereby the constituent of said fluid having a low boiling pointis evaporated lli Maaate first and withdrawn leaving Huid rich in thehigh boiling constituent, collecting for subsequent withdrawal at arelatively warm portion in said second device said fluid rich in highboiling constituent, by-passing gaseous fluid around said firstheat-transferring device and separately through said fluid rich in highboilingl constituent whereby the low boiling constituent in saidcollected fluid is evaporated and separated therefrom and whereby saidby-passed fluid is reduced in temperature, subjecting said by-passedcooled duid to evaporation and rectification in said secondheat-transferring device, and in passing one of the constituents ofrectification withdrawn from said second heattransferring device throughsaid first heattransferring device. r

6. lin apparatusof the class described, in combination,aheat-transferring device comprising successive portions maintained atprogressively varying temperatures, means for passing throughsuccessively warmer portions of said device a liquefied fluid forevaporating and rectifying said fluid whereby the constituent of saidfluid having a low boiling point is evaporated first leaving fluid richin the high boiling constituent, means for withdrawing said evaporatedlow boiling constituent, means for collecting said duid rich in highboiling constituent, auX- iliary means for heating said collected fluidto boil od the low boiling constituent contained therein, and means forwithdrawing from said collecting means the high boiling constituent. Y

7. ln apparatus of the classdescribed, in

p combination, aheat-transferring device comprising successive portionsmaintained at progressively varying temperatures, means for passingthrough successively warmer portions of said device a liquefied fluidwhereby the constituent of said duid having a low boiling point isprogressively evaporated through said successively warmer portions ofsaid device leaving fluid progressively richer in the high boilingconstituent as said evaporating duid approaches the warmer portions ofsaid device, means for collecting at a relatively warm portion of saiddevice said fluid rich in high boiling constituentaux iliarylheattransferring means positioned in'. said warmer portion. of saidheat-transferring device for maintaining said portion ofv said deviceand said collected fluid at a ternperature materially above the boilingpoint of said low boilingconstituent, means for withdrawing saidevaporated low boiling constituent, means for withdrawing said collecteduid, means for passgthrough said May, ieee..

auxiliary heat-transferring means gaseous fluid, and means fordischarging said fluid from said auxiliary heat-transferring means tosaid heat-transferring device for evaporation and rectification.

8. In apparatus of the class described, in combination, aheat-transferring device for cooling a gaseous fluid, a secondheat-trans ferring device maintained at progressively varyingtemperatures for liquefying the fluid, means for passing the liquefiedfluid through successively warmer portions of said secondheat-transferring device to evaporate and rectify first the low boilingconstituent thereof and to leave fluid rich in high boiling constituent,means for collecting said fluid richin high boiling constituent at a.relatively Warm portion of said second heat-transferring device, a thirdheattransferring device associated with the relatively warm portion ofsaid second heattransferring device, means for passing gaseous fluidaround said first heat-transferring device and through said thirdheattransferring device whereby the low boiling S5 constituent 'in saidcollected fluid is substantially entirely boiled ed 'and whereby saidfluid passing through said third heat-trans ferring device is reduced intemperature, and means for discharging said fluid from said thirdheat-transferring device to said second heat-transferring -deviceforeva-poration and rectification.

' 9. lin apparatus of the class described, in combination, aheat-transferring device for cooling a gaseous fluid, coils maintainedat progressively varying temperatures adapted for the passagetherethrough of said cooled fluid to liquefy it, a container surroundingsaid coils and providing a channel for the passage of fluid Within thecontainer and outside of said coils and in thermal contact with saidcoils, means for discharging said liquefied fluid from said coilsthrough progressively warmer portions of said channel whereby the lowboiling constituent of said Huid is evaporated and rectified first andwhereby fluid rich in high boiling constituent is adapt-ed to collect insaid container and at a relatively warm portion thereof, a coilpositioned within said container and substantiallyv at the warm portionof said channel vformed thereby for heating said collected Huid and forboiling ed` the low boiling constituent thereof, and means for passingthrough said coil uncooledduid.

lin testimony whereof, ll have sied my name'Y to this specification this9th day of lllltl

